The National Aeronautics and Space Administration (NASA) Science Mission Directorate (SMD) is releasing a NASA Announcement of Opportunity (NNH07ZDA003O), for the Explorer Program: Small Explorers (SMEX) and Missions of Opportunity. NASA expects to select up to three SMEX missions to proceed into Phase B and subsequent mission phases. NASA desires to launch the first SMEX mission by late 2011 or 2012; the launch-by date for all SMEX missions is April 30, 2014. One or more Missions of Opportunity, including participation in non-SMD space missions, small complete missions and new science missions using existing spacecraft, may also be selected. The science objectives covered by the AO include those of the SMD heliophysics research program and the astrophysics research program. Refer to the SMD World Wide Web homepage at http://science.hq.nasa.gov/ for further information about these programs.

Participation is open to all categories of organizations (U.S. and non-U.S), including educational institutions, industry, not-for-profit organizations, Federally Funded Research and Development Centers (FFRDCs), NASA Centers, the Jet Propulsion Laboratory (JPL), and other Government agencies. This solicitation will be open from September 28, 2007, through January 15, 2008. Upon the release date, the full text of the AO and all appendices will be available electronically via the World Wide Web site http://nspires.nasaprs.com/ .

A preproposal conference will be held November 6, 2007, in Washington, DC; see http://explorers.larc.nasa.gov/smexacq.html for details. Submission dates for PI pre-screening requests are Oct. 12, 26, November 16, and December 7, 2007.

This notice constitutes a NASA Research Announcement as contemplated in FAR 6.102(d)(2). Notwithstanding the posting of this opportunity at FedBizOpps.gov, Grants.gov, or at both sites, NASA reserves the right to determine the appropriate award instrument for each proposal selected pursuant to this announcement.